Alzheimer""s Disease (AD) is a degenerative brain disorder characterized clinically by progressive loss of memory, cognition, reasoning, judgment and emotional stability that gradually leads to profound mental deterioration and ultimately death. AD is a common cause of progressive mental failure (dementia) in aged humans and is believed to represent the fourth most common medical cause of death in the United States. AD has been observed in varied races and ethnic groups worldwide and presents a major present and future public health problem. The disease is currently estimated to affect about two to three million individuals in the United States alone. To date, AD has proven to be incurable.
The brains of individuals with AD exhibit neuronal degeneration and characteristic lesions variously referred to as amyloidogenic plaques, vascular amyloid angiopathy, and neurofibrillary tangles. Large numbers of these lesions, particularly amyloidogenic plaques and neurofibrillary tangles, are generally found in several areas of the human brain important for memory and cognitive function in patients with AD. Smaller numbers of these lesions in a more restricted anatomical distribution are found in the brains of most aged humans who do not have clinical AD. Amyloidogenic plaques and vascular amyloid angiopathy also characterize the brains of individuals with Trisomy 21 (Down""s Syndrome) and Hereditary Cerebral Hemorrhage with Amyloidosis of the Dutch-Type (HCHWA-D). At present, a definitive diagnosis of AD usually requires observing the aforementioned lesions in the brain tissue of patients who have died with the disease or, rarely, in small biopsied samples of brain tissue taken during an invasive neurosurgical procedure.
Several lines of evidence indicate that progressive cerebral deposition of particular amyloidogenic proteins, xcex2-amyloid proteins, (xcex2AP), play a seminal role in the pathogenesis of AD and can precede cognitive symptoms by years or decades. See, Selkoe, (1991) Neuron 6:487. Recently, it has been shown that xcex2AP is released from neuronal cells grown in culture and is present in cerebrospinal fluid (CSF) of both normal individuals and AD patients. See, Seubert et al., (1992) Nature 359:325-327.
In addition to Alzheimer""s Disease and other conditions associated with the amyloidogenic peptides xcex2AP, there exist conditions associated with other amyloidogenic peptides which are structurally similar to xcex2AP but which share no sequence homology with xcex2AP. Recent studies have demonstrated the functional interchangeability of many of these amyloidogenic peptides with regard to neurotoxicity. P. C. May, et al., Journal of Neurochemistry, (December 1993); co-pending U.S. patent application Ser. No. 08/109,782, filed Aug. 19, 1993 (Docket X-9342).
Despite the progress that has been made in understanding the underlying mechanisms of AD and other amyloidogenic protein related diseases, there remains a need to develop compositions and methods for treatment of these diseases. Treatment methods could advantageously be based on drugs which are capable of inhibiting the generation or effect of amyloidogenic proteins.
This invention encompasses methods for the inhibition of a physiological disorder associated with amyloidogenic proteins, which method comprises administering to a human in need thereof an effective amount of a compound of formula I 
wherein R1 and R3 are independently hydrogen, 
or 
wherein Ar is optionally substituted phenyl;
R2 is selected from the group consisting of pyrrolidino, hexamethylenemino, and piperidino; or a pharmaceutically acceptable salt of solvate thereof.
The present invention also provides a method of inhibiting amyloidogenic protein production comprising administering to a human in need thereof an effective amount of a compound of formula 1.
The present invention also provides a method of inhibiting the deposition of amyloid plaque comprising administering to a human in need thereof an effective amount of a compound of formula 1.
The present invention also provides a method of inhibiting Alzheimer""s Disease (AD) comprising administering to a human in need thereof an effective amount of a compound of formula 1.
The current invention concerns the discovery that a select group of benzothiophenes, those of formula I, are useful for inhibiting the effects of amyloidogenic proteins, and in particular the compounds inhibit amyloidogenic protein formation. The invention encompasses uses practiced by administering to a human in need thereof a dose of a compound of formula 1 or a pharmaceutically acceptable salt or solvate thereof effective to inhibit a physiological disorder associated with amyloidogenic proteins, and preferably xcex2-amyloid proteins.
The term xe2x80x9cinhibitxe2x80x9d includes its generally accepted meaning which includes prohibiting, preventing, restraining, and slowing, stopping, or reversing progression, severity, or a resultant symptom. As such, the methods include both therapeutic and prophylactic administration.
The term xe2x80x9cphysiological disorder associated with an amyloidogenic proteinxe2x80x9d includes diseases related to the innapropriate or undesirable deposition, such as in the brain, liver, kidney or other organ, of at least one amyloidogenic protein, and as such includes AD (includes familial AD), Down""s Syndrome, HCHWA-D, advanced aging of the brain and the like.
The term xe2x80x9ceffective amountxe2x80x9d means the amount of compound necessary to inhibit physiological effects or disorders associated with an amyloidogenic protein, or inhibit amyloidogenic production or deposition, or inhibit Alzheimers disease, as the case may be.
The term xe2x80x9camyloidogenic proteinxe2x80x9d as used herein refers to those peptides which have the ability to self-associate into higher ordered aggregates and eventually assemble into an amyloid plaque. The preferred target amyloidogenic proteins are xcex2-amyloid proteins.
Generally, the compound is formulated with common excipients, diluents or carriers, and compressed into tablets, or formulated as elixirs or solutions for convenient oral administration, or administered by the intramuscular or intravenous routes. The compounds can be administered transdermally, and may be formulated as sustained release dosage forms and the like.
The compounds used in the methods of the current invention can be made according to established and analogous procedures, such as those detailed in U.S. Pat. Nos. 4,133,814, 4,418,068, and 4,380,635 all of which are incorporated by reference herein. In general, the process starts with a benzo[b]thiophene having a 6-hydroxyl group and a 2-(4-hydroxyphenyl) group. The starting compound is protected, alkylated, and deprotected to form the formula I compounds. Examples of the preparation of such compounds are provided in the U.S. patents discussed above, and in the examples in this application. Optionally substituted phenyl includes phenyl and phenyl substituted once or twice with C1-C6 alkyl, C1-C4 alkoxy, hydroxy, nitro, chloro, fluoro, or tri(chloro or fluoro)methyl.
Included in this invention is the compound raloxifene, below: 
The compounds used in the methods of this invention form pharmaceutically acceptable acid and base addition salts with a wide variety of organic and inorganic acids and bases and include the physiologically acceptable salts which are often used in pharmaceutical chemistry. Such salts are also part of this invention. Typical inorganic acids used to form such salts include hydrochloric, hydrobromic, hydroiodic, nitric, sulfuric, phosphoric, hypophosphoric and the like. Salts derived from organic acids, such as aliphatic mono and dicarboxylic acids, phenyl substituted alkanoic acids, hydroxyalkanoic and hydroxyalkandioic acids, aromatic acids, aliphatic and aromatic sulfonic acids, may also be used. Such pharmaceutically acceptable salts thus include acetate, phenylacetate, trifluoroacetate, acrylate, ascorbate, benzoate, chlorobenzoate, dinitrobenzoate, hydroxybenzoate, methoxybenzoate, methylbenzoate, o-acetoxybenzoate, naphthalene-2-benzoate, bromide, isobutyrate, phenylbutyrate, xcex2-hydroxybutyrate, butyne-1,4-dioate, hexyne-1,4-dioate, caprate, caprylate, chloride, cinnamate, citrate, formate, fumarate, glycollate, heptanoate, hippurate, lactate, malate, maleate, hydroxymaleate, malonate, mandelate, mesylate, nicotinate, isonicotinate, nitrate, oxalate, phthalate, teraphthalate, phosphate, monohydrogenphosphate, dihydrogenphosphate, metaphosphate, pyrophosphate, propiolate, propionate, phenylpropionate, salicylate, sebacate, succinate, suberate, sulfate, bisulfate, pyrosulfate, sulfite, bisulfite, sulfonate, benzene-sulfonate, p-bromophenylsulfonate, chlorobenzenesulfonate, ethanesulfonate, 2-hydroxyethanesulfonate, methanesulfonate, naphthalene-1-sulfonate, naphthalene-2-sulfonate, p-toluenesulfonate, xylenesulfonate, tartarate, and the like. A preferable salt is the hydrochloride salt.
The pharmaceutically acceptable acid addition salts are typically formed by reacting a compound of formula I with an equimolar or excess amount of acid. The reactants are generally combined in a mutual solvent such as diethyl ether or benzene. The salt normally precipitates out of solution within about one hour to 10 days and can be isolated by filtration or the solvent can be stripped off by conventional means.
Bases commonly used for formation of salts include ammonium hydroxide and alkali and alkaline earth metal hydroxides and carbonates, as well as aliphatic and aromatic amines, aliphatic diamines and hydroxy alkylamines. Bases especially useful in the preparation of addition salts include ammonium hydroxide, potassium carbonate, sodium bicarbonate, calcium hydroxide, methylamine, diethylamine, ethylene diamine, cyclohexylamine and ethanolamine.
The pharmaceutically acceptable salts generally have enhanced solubility characteristics compared to the compound from which they are derived, and thus are often more amenable to formulation as liquids or emulsions.
Pharmaceutical formulations can be prepared by procedures known in the art. For example, the compounds can be formulated with common excipients, diluents, or carriers, and formed into tablets, capsules, suspensions, powders, and the like. Examples of excipients, diluents, and carriers that are suitable for such formulations include the following: fillers and extenders such as starch, sugars, mannitol, and silicic derivatives; binding agents such as carboxymethyl cellulose and other cellulose derivatives, alginates, gelatin, and polyvinyl pyrrolidone; moisturizing agents such as glycerol; disintegrating agents such as agaragar, calcium carbonate, and sodium bicarbonate; agents for retarding dissolution such as paraffin; resorption accelerators such as quaternary ammonium compounds; surface active agents such as cetyl alcohol, glycerol monostearate; adsorptive carriers such as kaolin and bentonite; and lubricants such as talc, calcium and magnesium stearate, and solid polyethyl glycols.
The compounds can also be formulated as elixirs or solutions for convenient oral administration or as solutions appropriate for parenteral administration, for instance by intramuscular, subcutaneous or intravenous routes. Additionally, the compounds are well suited to formulation as sustained release dosage forms and the like. The formulations can be so constituted that they release the active ingredient only or preferably in a particular part of the intestinal tract, possibly over a period of time. The coatings, envelopes, and protective matrices may be made, for example, from polymeric substances or waxes.
Compounds of Formula I can be administered for prophylactic and/or therapeutic treatment of diseases related to the deposition of one or more amyloidogenic proteins such as Alzheimer""s disease, Down""s syndrome, and advanced aging of the brain. In therapeutic applications, the compounds are administered to a host already suffering from a disease. The compounds are administered in an amount sufficient to inhibit physiological effects or disorders related to amyloidogenic protein, especially xcex2-amyloid proteins.
For prophylactic applications, the compounds of formula I are administered to a host susceptible to an amyloidogenic protein related disease, preferably Alzheimer""s disease, but not already suffering from such disease. Such hosts may be identified by genetic screening and clinical analysis, as described in the medical literature. see e.g., Goate, Nature, 349:704-706 (1991). The compounds will inhibit the amyloid protein plaque at a symptomatically early stage, preferably preventing even the initial stages of the amyloidogenic protein related disease. A preferred group for receiving compounds of the invention, either for prophylactic or therapeutic reasons, are post-menopausal women.
The particular dosage of a compound of formula I according to this invention will depend upon the severity of the condition, the route of administration, and related factors that will be decided by the attending physician. Generally, accepted and effective daily doses will be from about 0.1 to about 1000 mg/day, and more typically from about 50 to about 200 mg/day. Such dosages will be administered to a subject in need of treatment from once to about three times each day, or more often as needed, for a period of time sufficient to inhibit the disease or disorder.
Frequently, it will be desirable or necessary to introduce the pharmaceutical compositions directly or indirectly to the brain. Direct techniques usually involve placement of a drug delivery catheter into the host""s ventricular system to bypass the blood-brain barrier. Indirect techniques, which are generally preferred, involve formulating the compositions to provide for drug latentiation by the conversion of hydrophilic drugs into lipid-soluble drugs. Latentiation is generally achieved through blocking of the hydroxyl, carboxyl, and primary amine groups present on the drug to render the drug more lipid soluble and amenable to transportation across the blood-brain barrier. Alternatively, the delivery of hydrophilic drugs can be enhanced by intra-arterial infusion of hypertonic solutions which can transiently open the blood-brain barrier.
It is usually preferred to administer a compound of formula I in the form of an acid addition salt, as is customary in the administration of pharmaceuticals bearing a basic group, such as the piperidino ring. For such purposes the following dosage forms are available.